The present invention relates to a device for feeding blanks, for example, for containers to be filled with milk, and more particularly to a blank feeder for use with blanks folded flat so as to be unfoldable to a tubular form of square to rectangular cross section to feed each of the blanks to a bottom forming mandrel as stopped at a feed station by unfolding the blank to the tubular form and fitting the unfolded blank around the mandrel.
Feeders of the type mentioned above are already known which comprise a magazine having a delivery opening at one end and accommodating flat blanks as arranged closely side by side from this end toward the other end thereof, a transport arm for withdrawing the blank from the delivery opening and transporting the blank to a phantom extension of a mandrel, and means for unfolding the blank from the flat form to a tubular form of square cross section while the blank is being transported by the arm, the unfolding means having two unfolding claws provided at edge portions of the delivery opening so as to be engageable respectively with opposite ends of the blank to be withdrawn from the delivery opening.
With the conventional device described, the unfolding claws fail to fully unfold the blank and are likely to permit the blank as unfolded once an expanded state to restore itself to the original flat form during transport.